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we can do it

(12,116 posts)
Thu Jan 22, 2015, 07:03 PM Jan 2015

I had to put air in my tires when it was 5 below zero last week, the air pressure light came on.

Someone must have let the air out because they were properly inflated when I bought gas 2 days before and my car had been in the garage. I wonder if there is someone going around deflating things. This is very worrisome.

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I had to put air in my tires when it was 5 below zero last week, the air pressure light came on. (Original Post) we can do it Jan 2015 OP
Did you test them by kicking them? Could be someone is sneaking points onto shoes too uppityperson Jan 2015 #1
So you think the 2 lbs of pressure loss was natural? n/t dilby Jan 2015 #2
It was more than that! That's why I am so worried. It's a national crisis! we can do it Jan 2015 #3
Are You Sure You're Not Cheating?.....nt global1 Jan 2015 #4
Not me! You know, I think you get worse gas milage when you are under inflated.... we can do it Jan 2015 #7
Well, if the OP was in motorsport Blue_Tires Jan 2015 #18
it couldn't possibly be due to -5 temps, right? magical thyme Jan 2015 #48
Motorsport of course uses nitrogen for tire inflation Blue_Tires Jan 2015 #51
You gain the advantage of extra traction, but have no idea how it happened. jtuck004 Jan 2015 #5
Someone in Vegas probably has the odds on it. we can do it Jan 2015 #8
i suppose you MIGHT have a point if the tires on the other side of the car retained their pressure.. frylock Jan 2015 #6
But what if it was only the left tires that were deflated but the right side stayed the same? egduj Jan 2015 #9
It would be really weird. One tire had more air than the others...now that's worrisome. we can do it Jan 2015 #10
I've actually had a flat tire from leaving my car out in the cold. They tested the tire - no leaks. MANative Jan 2015 #11
Yep. Speaking as a Minnesotan who has experienced Antarctic temps hifiguy Jan 2015 #12
We had pretty low tires last time we went to Yellowstone. we can do it Jan 2015 #13
Thirty-something below temps in Vermont flattened all 4 of my tires. beam me up scottie Jan 2015 #14
No way. The temp for that game was 51 deg F. The temperature difference FSogol Jan 2015 #16
How unfortunate for the Patriots that the weather was so much warmer on the other side of the field mythology Jan 2015 #41
Let us know if that happens when it's 50+ degrees, not 5 below. pnwmom Jan 2015 #15
Ideal Gas Law former9thward Jan 2015 #21
But we can skip all those calculations because . . . pnwmom Jan 2015 #22
Depends how they were inflated. NutmegYankee Jan 2015 #24
And why would the Colts have purposely made their balls harder to catch? pnwmom Jan 2015 #25
Each QB has their favorite feel. NutmegYankee Jan 2015 #26
The refs used equipment to test the balls beforehand -- they weren't relying pnwmom Jan 2015 #29
Do you understand physics? NutmegYankee Jan 2015 #30
Do you? Both teams' balls underwent the same temperature fluctuations pnwmom Jan 2015 #32
You've ignored my last two posts explaining that quite clearly. NutmegYankee Jan 2015 #33
And if you are correct, then the league would simply announce pnwmom Jan 2015 #35
I figure they are still investigating while the media hypes, like usual. NutmegYankee Jan 2015 #37
They are even dumber than usual, then. Because they've been letting this story pnwmom Jan 2015 #38
NFL management is just a bunch of assclowns. NutmegYankee Jan 2015 #42
Who knows where the balls were stored or measured. former9thward Jan 2015 #46
The Patriots know. And if the storage conditions or other logical reasons pnwmom Jan 2015 #47
The Pats are not going to speak while the NFL investigates. former9thward Jan 2015 #49
Yup.And what kind of investigation wouldn't start with them speaking to the QB? pnwmom Jan 2015 #52
They could have talked to the officials, equipment manager former9thward Jan 2015 #54
That would be great if balls had rigid walls jberryhill Jan 2015 #28
Ball bladder are normally made of Butyl rubber, which has low elasticity compared to other rubbers. NutmegYankee Jan 2015 #31
At these pressures, it matters jberryhill Jan 2015 #44
Meanwhile, the NFL ruled out the temperature as a factor MohRokTah Jan 2015 #17
Science doesn't support that assertion though madokie Jan 2015 #20
Yes, science does support that assertion. pnwmom Jan 2015 #23
Good point madokie Jan 2015 #19
... pinboy3niner Jan 2015 #27
Same here I had the TPM light come on. I put 30 pounds in all 4 tires doc03 Jan 2015 #34
100% Nitrogen won't change it much. The atmosphere is 78% Nitrogen. NutmegYankee Jan 2015 #36
When nitrogen is seperated from compressed air there is doc03 Jan 2015 #39
You can get dry air like that too. NutmegYankee Jan 2015 #40
We had an air dryer system but it wasn't 100%, still got some water doc03 Jan 2015 #56
When I bought my 09 Cobalt new Omaha Steve Jan 2015 #43
It will definently help with fires - it's totally inert. NutmegYankee Jan 2015 #45
I suspect various grades of low water vapor air would work just as well Major Nikon Jan 2015 #55
Nitrogen is used for aircraft that fly at very high altitudes Major Nikon Jan 2015 #53
You need to be disqualified from posting on DU Capt. Obvious Jan 2015 #50

we can do it

(12,116 posts)
3. It was more than that! That's why I am so worried. It's a national crisis!
Thu Jan 22, 2015, 07:18 PM
Jan 2015

I was able to drive to a gas station normally though, without damage. But they were UNDERINFLATED OMG!!!!1111

we can do it

(12,116 posts)
7. Not me! You know, I think you get worse gas milage when you are under inflated....
Thu Jan 22, 2015, 07:35 PM
Jan 2015

maybe it was the gas companies. Quick everyone check your tires!!!!

Blue_Tires

(55,445 posts)
18. Well, if the OP was in motorsport
Thu Jan 22, 2015, 08:45 PM
Jan 2015

and his tire inflation "just happened" to be 11%-13% outside of the regulation norms, then the stewards might want to have a chat...

 

magical thyme

(14,881 posts)
48. it couldn't possibly be due to -5 temps, right?
Fri Jan 23, 2015, 11:47 AM
Jan 2015

Tire pressure (per square inch) drops between one and two pounds for every 10-degree decrease in temperature, and that can make a big difference to a driver who hasn’t filled up since summer.

On a day like today, when the low temperature was 24 degrees, your tires could be 5 to 10 pounds per square inch lower than they were on a 74-degree morning.

So even if you filled up to a comfortable PSI of 32 in August, your tires could have dropped as much as 25 percent by today — which in most cars is enough to trigger a warning.

http://www.bostonglobe.com/metro/2014/11/19/cold-you-should-check-your-tire-pressure/eYdwB6XCZsaOGDmd31LBFI/story.html

Blue_Tires

(55,445 posts)
51. Motorsport of course uses nitrogen for tire inflation
Fri Jan 23, 2015, 02:14 PM
Jan 2015

which is much more stable in temperature swings than generic 'air' from the local gas station....

 

jtuck004

(15,882 posts)
5. You gain the advantage of extra traction, but have no idea how it happened.
Thu Jan 22, 2015, 07:26 PM
Jan 2015

I mean, what are the odds of that.

frylock

(34,825 posts)
6. i suppose you MIGHT have a point if the tires on the other side of the car retained their pressure..
Thu Jan 22, 2015, 07:33 PM
Jan 2015

apparently, the Colts had an entirely different weather system on their side of the field.

egduj

(804 posts)
9. But what if it was only the left tires that were deflated but the right side stayed the same?
Thu Jan 22, 2015, 07:38 PM
Jan 2015

That would be weird!

MANative

(4,105 posts)
11. I've actually had a flat tire from leaving my car out in the cold. They tested the tire - no leaks.
Thu Jan 22, 2015, 07:43 PM
Jan 2015

My mechanic said it was very common. I think "Deflategate" was a natural occurrence.

 

hifiguy

(33,688 posts)
12. Yep. Speaking as a Minnesotan who has experienced Antarctic temps
Thu Jan 22, 2015, 07:51 PM
Jan 2015

in the winter, I can tell you that in very cold subzero temps the air becomes more dense and takes up less space in the tire - seriously. It's the same reason that if you live next to an airport it sounds like jets are flying ten feet over your house when they take off when it is too frikkin' cold outside: Uncommonly dense air, which acts as a more efficient transmitter of sound.

Weird science!!

we can do it

(12,116 posts)
13. We had pretty low tires last time we went to Yellowstone.
Thu Jan 22, 2015, 07:58 PM
Jan 2015

Picked up the car at airport in Billings, drove the Beartooth highway and stayed in Cooke City overnight. Got up early (was like 42 degrees about 35degrees colder than when we got the car) and the tires were nearly flat- drove next door and the gas station lady said it happens all the time)

beam me up scottie

(57,349 posts)
14. Thirty-something below temps in Vermont flattened all 4 of my tires.
Thu Jan 22, 2015, 08:36 PM
Jan 2015

I called my brother who was unable to bring me to work because his fuel line was frozen.

Boy that was a sucky day.

FSogol

(45,355 posts)
16. No way. The temp for that game was 51 deg F. The temperature difference
Thu Jan 22, 2015, 08:43 PM
Jan 2015

air in ball vs outside air is not great enough to cause deflation. A human deflated the ball.

 

mythology

(9,527 posts)
41. How unfortunate for the Patriots that the weather was so much warmer on the other side of the field
Thu Jan 22, 2015, 11:19 PM
Jan 2015

After all, that must be the reason why the Colts' footballs were still at the legal inflation.

pnwmom

(108,925 posts)
15. Let us know if that happens when it's 50+ degrees, not 5 below.
Thu Jan 22, 2015, 08:39 PM
Jan 2015

Or maybe 50 degrees is just much much colder in Boston than it is anywhere else?

former9thward

(31,798 posts)
21. Ideal Gas Law
Thu Jan 22, 2015, 09:01 PM
Jan 2015

To answer this question, let's begin with a little equation you may or may not remember from chemistry or physics, back in high school. It's called the Ideal Gas Law:

pV=nRT
where p is pressure, v is volume, n is the number of moles of a gas, R is the Universal Gas constant, and T is temperature.

Remember, what we do to one side of the equation, we have to do to the other side as well. For example, if we increase the pressure (p), then the temperature (T) would have to increase as well. That also means that a change in volume (V) would mean a change in temperature.

We make the following assumptions, based on what we know about the procedure regarding regulation footballs in the NFL and about the Ideal Gas Law:

1) V, the volume of gas (air) in the ball should not change, since (according to procedure), no air is added to or subtracted from the ball after reaching the proper inflation,

2) n will not change for the same reason as above,

3) R does not change, since it is a universal constant.

Now, let's just change the way the equation looks by moving all the letters to one side of the equation:

pV/nRT = 1
From here, we need to think of this as two different times: the pressure, temperature, etc. from when the balls were checked and the pressure, temperature, etc. out on the field. Let's set those to be equal:

p1 V1 / n1 RT1 = p2 V2 / n2 RT2,
where the 1 represents the initial readings and 2 represents the readings on the field. Since the volume will not change (assuming no air is added or taken away from the ball), then V1 = V2, and those can be cancelled. For the same reason, n1 andn 2 can cancel. The R 's cancel, since R

is a constant. We are left with a simple equation:

p1 / T1 = p2 / T2
Now, we can start solving this puzzle quite easily! But before we do, we also have to know the atmospheric pressure during the game, since p in this case is the absolute pressure; the pressure inside the ball plus the pressure of the atmosphere (which exerts a force on the ball as well).

At 6pm, the atmospheric pressure at nearby Norwood Airport was 1009.5 mb (1009.5 hPa or 100950 Pa).

Let's assume that each ball was inflated to the minimum pressure required to meet the NFL rules regarding proper inflation: 12.5 psi. We convert psi (English) to pascals (Metric), which comes out to 86,184.5 Pa and assume a room temperature of 68ºF (20ºC) which converts to 293.15 K (Kelvin, the Metric equivalent). We now have,

(86,184.5 Pa + 100950.0 Pa) / 293.15 K = (p2 + 100950.0 Pa) / T2.
We're down to two variables. But we also know the temperature on the field at the start of the game was reported as 51ºF/10.6ºC (283.15 K). Plug it in...

(86,184.5 Pa + 100950.0 Pa) / 293.15 K = (p2 + 100950.0 Pa) / 283.15 K
Neat! Look, we're left with a solvable equation with one variable, p2, which is the pressure of the air inside the ball at game time! Let's solve this riddle...

Isolate the lone variable:

{[(86,184.5 Pa + 100950.0 Pa) / 293.15 K] * 283.15 K} - 100950.0 Pa = p2
79,800.9 Pa = p2 ---> 11.8 psi
83,244.6 Pa is 11.8 psi, so, according to these calculations, the balls could have been under-inflated by 0.7 psi on the field, just due to the change in temperature from inside to outside. This makes sense given the very first equation, which shows that a decrease in temperature would force a decrease in pressure, assuming the same volume of air in the football.

If we use an indoor temperature of 80º, we would get a final pressure of 11.0 (10.99) psi.


http://www.wcsh6.com/story/weather/2015/01/20/inflate-gate-weather-roll/22065861/

pnwmom

(108,925 posts)
22. But we can skip all those calculations because . . .
Thu Jan 22, 2015, 10:07 PM
Jan 2015

The Colts' balls underwent the same weather and testing conditions as the Patriots' balls. And all the Colts balls tested within regulation limits.

(And why would anyone use an indoor temperature of 80 instead of 70?)

NutmegYankee

(16,177 posts)
24. Depends how they were inflated.
Thu Jan 22, 2015, 10:14 PM
Jan 2015

A motorized pump usually heats the air from compression. The Colts may have inflated their balls towards the high end of the scale and used manual pumps while the Pats used a motorized pump and left the balls at the low end.

pnwmom

(108,925 posts)
25. And why would the Colts have purposely made their balls harder to catch?
Thu Jan 22, 2015, 10:17 PM
Jan 2015

And the league tested all the balls before they went into the game. Why hasn't the league simply announced that the Colts' balls started out significantly heavier than the Patriots' balls? Instead of letting all this furor go on?

NutmegYankee

(16,177 posts)
26. Each QB has their favorite feel.
Thu Jan 22, 2015, 10:22 PM
Jan 2015

The only one throwing the ball is him. Some actually prefer them even harder than regulation. They tailor it for their taste and have the receivers train to catch them.

In reality, 10.5 and 12.5 isn't a huge difference. You have to have a damn good handgrip to notice, which is why the refs probably never did.

pnwmom

(108,925 posts)
29. The refs used equipment to test the balls beforehand -- they weren't relying
Thu Jan 22, 2015, 10:35 PM
Jan 2015

on their hands to judge.

If this problem were simply explained away, as you have tried to do, the League would have done this by now. Instead it's standing back while everyone says, "Ask the other guy. It's not me!"

NutmegYankee

(16,177 posts)
30. Do you understand physics?
Thu Jan 22, 2015, 10:38 PM
Jan 2015

If the air is warmer than room temp in the ball at test time, insulated by a bladder and skin that don't transfer heat well, the pressure will be within spec at test time - which is all that matters. Later, the air comes to equilibrium with the much cooler outside air over two hours, and is now low. HAPPENS EVERY GAME.

pnwmom

(108,925 posts)
32. Do you? Both teams' balls underwent the same temperature fluctuations
Thu Jan 22, 2015, 10:49 PM
Jan 2015

and were tested under the same conditions.

And yet, magically (or not), only one set of balls turned out to be at least 2 pounds underweight, in 11 out of 12 cases.

Sorry, but physics doesn't explain that.

NutmegYankee

(16,177 posts)
33. You've ignored my last two posts explaining that quite clearly.
Thu Jan 22, 2015, 10:55 PM
Jan 2015

I guess you see physics as magic.

And yes, I understand physics quite well - I'm a professional Mechanical Engineer who works on compressed gas systems.

pnwmom

(108,925 posts)
35. And if you are correct, then the league would simply announce
Thu Jan 22, 2015, 10:58 PM
Jan 2015

your explanation as the correct one.

You think they wouldn't tell us if the teams used different methods for inflating their balls? Right. Under all this pressure, they're not offering us that simple explanation.

Because it isn't true.

NutmegYankee

(16,177 posts)
37. I figure they are still investigating while the media hypes, like usual.
Thu Jan 22, 2015, 10:59 PM
Jan 2015

And the haters hate, like usual.

pnwmom

(108,925 posts)
38. They are even dumber than usual, then. Because they've been letting this story
Thu Jan 22, 2015, 11:03 PM
Jan 2015

hang out for days, letting this whole scandal suck the air out of the Super Bowl, when -- according to you -- they could have just explained all this away a long time ago.

Not likely.

former9thward

(31,798 posts)
46. Who knows where the balls were stored or measured.
Fri Jan 23, 2015, 01:48 AM
Jan 2015

Were the Colts balls and the Pats balls in the same place when measured. I don't know.

pnwmom

(108,925 posts)
47. The Patriots know. And if the storage conditions or other logical reasons
Fri Jan 23, 2015, 02:10 AM
Jan 2015

explained it, why aren't they and the League speaking out?

If there was an innocent explanation don't you think they'd have figured it out by now?

former9thward

(31,798 posts)
49. The Pats are not going to speak while the NFL investigates.
Fri Jan 23, 2015, 11:59 AM
Jan 2015

I really don't get the NFL investigation. Brady said yesterday they had not spoke to him. I would think he would be the first person they talked to.

pnwmom

(108,925 posts)
52. Yup.And what kind of investigation wouldn't start with them speaking to the QB?
Fri Jan 23, 2015, 02:49 PM
Jan 2015

And this is the 5th day now.

former9thward

(31,798 posts)
54. They could have talked to the officials, equipment manager
Fri Jan 23, 2015, 03:03 PM
Jan 2015

ball runners, QB, and coach in a days time. It is not that hard and Goodell has the power to do that. Maybe they want to push it back to after the Super Bowl. I don't know.

 

jberryhill

(62,444 posts)
28. That would be great if balls had rigid walls
Thu Jan 22, 2015, 10:31 PM
Jan 2015

"Since the volume will not change (assuming no air is added or taken away from the ball)..."

The volume of an elastic container is a function of the pressure. It is not a constant for this model.

 

MohRokTah

(15,429 posts)
17. Meanwhile, the NFL ruled out the temperature as a factor
Thu Jan 22, 2015, 08:43 PM
Jan 2015

In the deflated balls cheat by the Patriots.

Weird that, eh?

madokie

(51,076 posts)
20. Science doesn't support that assertion though
Thu Jan 22, 2015, 08:50 PM
Jan 2015

If I had a foot ball I'd make a check just to satisfy myself on this.

pnwmom

(108,925 posts)
23. Yes, science does support that assertion.
Thu Jan 22, 2015, 10:09 PM
Jan 2015

Because science would tell us that the Colts' balls experienced the same temperature and testing conditions as the Patriots balls, and therefore the effect should have been the same on all the balls. But only the Patriots' balls tested underweight.

madokie

(51,076 posts)
19. Good point
Thu Jan 22, 2015, 08:48 PM
Jan 2015

I say its our neighbors who do that to us

from a room temperature ball to a sideline ball there would definitely be a difference in the pressure

doc03

(35,143 posts)
34. Same here I had the TPM light come on. I put 30 pounds in all 4 tires
Thu Jan 22, 2015, 10:56 PM
Jan 2015

a couple months ago when the weather was warmer. The tires on the truck read between 26.5 to 27.5 pounds. I brought them all up to 30 pounds and the TPM light was still on. I checked the spare and it was at 24.5 pounds, I remembered I hadn't check it since in the summer when it was in the 80s. Air pressure can vary several pounds with temperature. I hear if you inflate your tires with nitrogen you don't have that problem. Maybe they could use nitrogen in footballs.

NutmegYankee

(16,177 posts)
36. 100% Nitrogen won't change it much. The atmosphere is 78% Nitrogen.
Thu Jan 22, 2015, 10:58 PM
Jan 2015

And oxygen reacts very much the same. At least, at the temps we normally encounter.

doc03

(35,143 posts)
39. When nitrogen is seperated from compressed air there is
Thu Jan 22, 2015, 11:08 PM
Jan 2015

no water vapor in it. We used nitrogen in our pneumatic impulse lines in the steel mill because we couldn't chance having the lines freeze up in cold weather.

NutmegYankee

(16,177 posts)
40. You can get dry air like that too.
Thu Jan 22, 2015, 11:18 PM
Jan 2015

It just requires a dehydrator system. We use them in my industry for our compressed air. But I'm sure a nitrogen like MIL-PRF-27401 Type I Grade B and C would do the trick for freezing.

doc03

(35,143 posts)
56. We had an air dryer system but it wasn't 100%, still got some water
Fri Jan 23, 2015, 03:33 PM
Jan 2015

in the lines. Had lots of problems in the winter.

Omaha Steve

(99,054 posts)
43. When I bought my 09 Cobalt new
Thu Jan 22, 2015, 11:31 PM
Jan 2015

They did Nitrogen in the tires for free. There is a difference.

Some believe it helps with tire fires too.

NutmegYankee

(16,177 posts)
45. It will definently help with fires - it's totally inert.
Thu Jan 22, 2015, 11:44 PM
Jan 2015

The only reason I think you see a difference when they use nitrogen is they use pure nitrogen, while the air is whatever is outside (humidity and all) simply compressed. If you used CGA grade scuba air, I'd expect a similar result.

I use nitrogen when testing 100% oxygen systems because it acts like oxygen, but isn't a fire hazard if it's leaking.

Major Nikon

(36,814 posts)
55. I suspect various grades of low water vapor air would work just as well
Fri Jan 23, 2015, 03:07 PM
Jan 2015

But I'm not so sure they would be cheaper. Compressed nitrogen is very cheap to produce and transport.

Major Nikon

(36,814 posts)
53. Nitrogen is used for aircraft that fly at very high altitudes
Fri Jan 23, 2015, 02:58 PM
Jan 2015

...for a good reason.

As someone pointed out, it's not so much the difference in gases, but rather the difference in water vapor.

Capt. Obvious

(9,002 posts)
50. You need to be disqualified from posting on DU
Fri Jan 23, 2015, 12:44 PM
Jan 2015

and someone that was banned should be allowed to take your place.

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